1. Field of the Invention
This invention relates primarily to fuel injection devices and more specifically to a new and improved means of transforming atomized liquid fuel to a gaseous or vaporized state for more efficient combustion in an internal combustion engine or furnace. The same device can also be put to use in many other processes other than combustion, such as disbursing and fogging, or any application that requires the transformation of a liquid to a gas efficiently at a specific point in a process.
2. Background of the Invention
Through my research in the field of carburetion and fuel injection systems incorporating fuel heating or vaporizing devices of which the instant invention shares a common purpose, it has become apparent that there are four general approaches by which the heating of liquid fuel to a vaporized or gaseous state is being accomplished.
The first approach involves the recycling of exhaust gases to a heat exchanger in the carburetor for the purpose of fuel vaporization, an example of which is U.S. Pat. No. 4,336,784 to Gotoh, Otobe, Kawamoto, and Fujimura issued on Jun. 29, 1982. The disadvantage to this arrangement is that vaporized fuel is not available until after the engine has started so that the device is of no help in starting engines at low ambient temperatures.
The second approach involves the circulating of heated engine cooling water through a heat exchanger in or under the carburetor for the purpose of fuel vaporization, an example of which is U.S. Pat. No. 4,286,564 issued to Van Tuyl on Sep. 1, 1981. This approach suffers from the same deficiency as in Gotoh (U.S. Pat. No. 4,336,784) cited above.
The third approach involves the use of electrical heating devices located in the carburetor or between the carburetor and intake manifold for the purpose of vaporizing fuel.
The following are examples of electrical heating devices located between a carburetor or throttle body and the intake manifold of an internal combustion engine. U.S. Pat. No. 4,108,953 issued to Rocco on Aug. 22, 1978, U.S. Pat. No. 4,106,454 issued to Jasper and Ball on Aug. 15, 1978, U.S. Pat. No. 4,020,812 issued to Hayward on May 3, 1977, and U.S. Pat. No. 2,700,722 issued to Keuhl on Jan. 25, 1955. All of the claimed devices of the aforementioned art employ heat conducting screens that are in contact with electrical resistance heaters. This configuration is not an efficient heat exchanger. Another disadvantage to this approach is that inlet air is restricted. A third problem with this approach is that in order to vaporize a relatively small volume of liquid or atomized fuel, a tremendous volume of air must also be heated making this an impractical fuel vaporization means.
U.S. Pat. No. 4,528,967 issued to Bart on Jul. 16, 1985, sets forth a throttle body fuel system which employs an electrically heated annular venturi section. The heated venturi is comprised of a metal tubular component in contact with a resistance heating element segregated from the main throttle body by means of a thermal insulator. The tubular metal component has a series of holes straight through its wall intended to vaporize fuel as it passes through the component into the throat of the venturi. A disadvantage of this arrangement is the inefficiency of the tubular member employing holes straight through its wall as a heat exchanger. Another drawback is that an engine backfire could flash back through the series of holes provided in the tubular component for the purpose of fuel passage, thereby enabling flame to burn in the annular void surrounding the heated venturi. The drawings for the preferred embodiment of this throttle body show two diametrically opposed nozzles as the atomized fuel source. With this arrangement it would be difficult to distribute fuel evenly around the outside circumference of the fuel heating element.
U.S. Pat. No. 3,915,137 issued to Evans on Oct. 28, 1975 sets forth a heating coil that is located beneath the fuel jet in a venturi associated with a carburetor. The inefficiency of the heat exchanger design, and the fact that the heater is located in the center of the inlet air stream whereby a large volume of air passing by the element would have to be heated in addition to the relatively small volume of liquid fuel makes this device impractical for a fuel vaporizer. U.S. Pat. No. 4,458,654 issued to Tuckey on Jul. 10, 1984 suffers from the same short-coming as does the previous example.
A number of fuel heating devices are known in the art that employ positive temperature coefficient thermistors as a fuel vaporization devices.
U.S. Pat. No. 4,651, 702 issued to Nara, Yazawa, and Akiyama on Mar. 24, 1987 and U.S. Pat. No. 4,398,522 issued to Kuroiwa, Kato, and Ando on Aug. 16, 1983 are examples of this technology employed in tubular configurations and located between the carburetor and intake manifold associated with an internal combustion engine. A drawback of this approach is that only fuel that contacts the heating element is vaporized leaving the majority of the fuel that passes by the element unheated. Another drawback is that when the thermistor is located between the carburetor and intake manifold it is necessary to heat a large volume of air in order to heat a small volume of fuel making this approach inefficient.
U.S. Pat. No. 4,387,690 issued to Chivaroli in June of 1983 sets forth a PTC heating element located in the intake manifold of an internal combustion engine for the purpose of fuel vaporization. A deficiency of this configuration is its inefficiency as a fuel vaporizer due to the fact that air must be heated as well as fuel. In addition it is restrictive of air inlet flow.
U.S. Pat. No. 4,356,804 issued to Igashira, Nomura, and Abe on Nov. 2, 1982 sets forth a heated plate beneath a carburetor and suffers from the same inefficiency as does the previous example.
U.S. Pat. No. 4,212,275 issued to Inone on Jul. 15, 1980, sets forth an embodiment consisting of a 3-dimensionally porous positive temperature coefficient thermistor of an annular configuration located in the venturi section of a carburetor so as to become the outside wall of the venturi. The PTC thermistor is subjected to electric current so as to become heated. The PTC thermistor then autostabilizes its temperature at the optimum temperature for vaporizing gasoline that is drawn through it due to engine vacuum. The thermistor element makes electrical contact at its outside diameter with the carburetor body and at its inside diameter with a metal aperture ring perforated with a series of holes. This configuration suffers from deficiencies that would make it impractical for its intended application.
This embodiment will not vaporize all of the fuel drawn through the carburetor. Only a portion of the fuel which actually passes through the pores of the thermistor would be transformed leaving a large percentage of fuel unchanged. There is a question as to whether gasoline having a much higher viscosity than the inlet air with which it is mixed would actually pass through the pores of the element at all. In any case, a large volume of inlet air can be expected to pass through the pores of the element. This phenomena would cause two problems. First it would tend to greatly cool the porous thermistor causing its electrical resistance to become lowered thereby increasing its current flow and decreasing its efficiency as a fuel vaporizer considerably. Secondly contaminants in the inlet air which would be extremely difficult to remove sufficiently even after filtering. Air would pass continuously through the pores of the thermistor element causing it to become clogged in the same manner as an air filter becomes clogged necessitating frequent replacement or cleaning of the porous element.
This embodiment has considerable thermal mass making it sluggish to respond to changes in fuel flow, it also can be expected to have a wicking effect causing engine responsiveness to suffer.
In addition, the porous PTC ceramic is intended to absorb some portion of fuel that flows through the conduit due to engine vacuum where it is to be vaporized and returned to the conduit downstream. It is doubtful that any significant portion of the fuel flow would actually find its way through the holes in the wall of the conduit and into the porous ceramic element. More likely the fuel flow would take the path of least resistance and flow straight through the conduit. Any fuel that did find its way into the porous ceramic element would immediately be vaporized causing an increase in pressure within the ceramic body, thereby tending to prevent additional fuel from entering the ceramic element's pores.
Several vaporizer type fuel injectors are known that utilize electrical heat sources for the purpose of vaporizing fuel supplied by an injector. These devices are intended primarily for self-igniting internal combustion engines whereby fuel is injected directly into the combustion chamber as opposed to into the air inlet system of an engine or furnace as would be the case with the instant invention. Generally, these devices employ electrically heated cylindrical areas or coiled resistance wire located at the tip of the injector nozzle. It is presumed that some of these devices might also be employed as gasoline fuel injectors or oil burner nozzles, however there efficiency would be less than the porous thermistor utilized in the instant invention. The following are some examples of this technology. U.S. Pat. No. 4,760,818 issued to Brook on Aug. 2, 1988, U.S. Pat. No. 4,603,667 issued to Grunwald on Aug. 5, 1986, U.S. Pat. No. 4,627,405 issued to Imhof on Dec. 9, 1986, and U.S. Pat. No. 4,834,043 issued to Kacxynaki on May 30, 1989.